We stayed about a week at Parn's apartment. It's very clean and everything is new. We had a great time there.
It's also very close to the bts, although it's a bit far from the main attractions (30-40 minutes in the bts to reach the commercial center, a bit more to get to the golden palace, chatuchak market and khaosan road).
There's a small kitchen, although we didn't get to cook there, specially because eating out in Bangkok is not that expensive.